Suppression of Auger Cross Relaxation in Mn-Doped Core-Shell Perovskite Nanocrystals via Wave Function Engineering.

Mn-doped perovskite nanocrystals (NCs) exhibit great application potential because of their unique optical properties. However, the long-lived nature of excited Mn easily leads to the coexistence of excited Mn and host excitons in a single NC, which inevitably induces an Auger cross relaxation between them, thus significantly limiting the luminescent efficiency of Mn due to its competition with internal energy transfer. Herein, we design and prepare a kind of Mn-doped core-shell CsPbCl@CsPbCl perovskite NC with Mn doped only in the shell layer, which is expected to suppress this Auger process by spatially separating the electronic wave functions.

Amplified Detection of Threading Dislocations in n-Type 4H-SiC Epilayers Enabled by Time-Resolved Photoluminescence Mapping.

Threading dislocations (TDs) in epitaxial layers of silicon carbide (SiC) exert a negative impact on the device performance, thereby hampering the commercialization of SiC power devices. Therefore, inspection of TD defects is a crucial step in the fabrication of SiC wafers. In this work, we reported a time-resolved photoluminescence (PL) mapping technique for detecting TDs by extracting PL images at different delay times after pulse excitation along the lifetime decay curve.

Visualizing Ultrafast Photogenerated Electron and Hole Separation in Facet-Engineered Bismuth Vanadate Crystals.

Photogenerated charge separation is pivotal for effecting efficient photocatalytic reactions. Understanding this process with spatiotemporal resolution is vital for devising highly efficient photocatalysts. Here, we employed pump-probe transient reflection microscopy to directly observe the temporal and spatial evolution of photogenerated electrons and holes on the surface of facet-engineered bismuth vanadate (BiVO) crystals.

Elucidating the Impact of Electron Accumulation in Quantum-Dot Light-Emitting Diodes.

Quantum-dot (QD) light-emitting diodes (QLEDs) are promising candidates for future display technology. An imbalance in the injection of electrons and holes into QLEDs leads to the accumulation of excess charges, predominantly electrons, in the QDs. The precise effects of these accumulated electrons have not yet been fully quantified.

Probing the Operation of Quantum-Dot Light-Emitting Diodes Using Electrically Pumped Transient Absorption Spectroscopy.

The quantum-dot light-emitting diode (QLED) is a new generation light emission source that holds great promise for display and lighting applications. Understanding the dynamics of electrons and holes in QLEDs during their operation is crucial for future QLED optimization, but a time-resolved technology capable of characterizing electrons is still lacking. To tackle this challenge, we develop a unique electrically pumped transient absorption (E-TA) spectroscopy to probe the density of electrons in the QD layer with a nanosecond time resolution.

Trap-Induced Long-Lived Internal Charge Separation in Sn-Doped MAPbBr Perovskite Films.

Sn-doped lead halide perovskites (LHPs) have attracted considerable attention for their lower bandgap and lower toxicity. While it is well-established that Sn doping easily introduces a lot of structural defects into LHP films, the extent to which these defects impact carrier dynamics has yet to be fully elucidated. Herein, we take Sn-doped MAPbBr films as an example to explore the influence of Sn doping on their carrier dynamics.

Printable Block Molecular Assemblies with Controlled Exciton Dynamics.

Creating hierarchical molecular block heterostructures, with the control over size, shape, optical, and electronic properties of each nanostructured building block can help develop functional applications, such as information storage, nanowire spectrometry, and photonic computing. However, achieving precise control over the position of molecular assemblies, and the dynamics of excitons in each block, remains a challenge. In the present work, the first fabrication of molecular heterostructures with the control of exciton dynamics in each block, is demonstrated.

Achieving Highly Efficient Warm-White Light Emission in All-Inorganic Copper-Silver Halides via Structural Regulation.

Single-component metal halides with white light emission are highly attractive for solid-state lighting applications, but it is still challenging to develop all-inorganic lead-free metal halides with high white-light emission efficiency. Herein, by rationally introducing silver (Ag) into zero-dimensional (0D) Cs Cu Br as new structural building unit, a one-dimensional (1D) bimetallic halide Cs Cu AgBr is designed that emits strong warm-white light with an impressive photoluminescence quantum yield (PLQY) of 94.5% and excellent stability.

Morphology-Dependent Carrier Accumulation Dynamics in Mixed Halide Perovskite Thin Films Caused by Phase Segregation.

The phase segregation in mixed halide perovskites is recently found to improve the photoluminescence quantum yield (PLQY) of the perovskites by concentrating the carriers. However, how phase segregation affects the photoinduced carrier dynamics is unclear. Herein, we find that the phase segregation in CHNHPbBrI mixed halide perovskite thin film is morphology-dependent by showing I-rich domains mainly along the grain boundaries.

Lattice distortion inducing exciton splitting and coherent quantum beating in CsPbI perovskite quantum dots.

Anisotropic exchange splitting in semiconductor quantum dots results in bright-exciton fine-structure splitting important for quantum information processing. Direct measurement of fine-structure splitting usually requires single/few quantum dots at liquid-helium temperature because of its sensitivity to quantum dot size and shape, whereas measuring and controlling fine-structure splitting at an ensemble level seem to be impossible unless all the dots are made to be nearly identical. Here we report strong bright-exciton fine-structure splitting up to 1.

Co-Doped Mn O Nanocubes via Galvanic Replacement Reactions for Photocatalytic Reduction of CO with High Turnover Number.

The synthesis of Co-doped Mn O nanocubes was achieved via galvanic replacement reactions for photo-reduction of CO . Co@Mn O nanocubes could efficiently photo-reduce CO to CO with a remarkable turnover number of 581.8 using [Ru(bpy) ]Cl  ⋅ 6H O as photosensitizer and triethanolamine as sacrificial agent in acetonitrile and water.